Formatting table - why does '\t' get changed?

Question

I want to format a grid nicely. It is 9x9 grid. I want to delimit it

after every 3rd column - put "*"

else - '\t'.

after every 3rd row put "-------------------------"

Horizontal line works nicely - this is easy.

But in column 3 it starts printing only 2-3 spaces instead of '\t'.

The code:

  static int grid[9][9] ;

void print_grid(){
     cout << "PRINTING GRID" <<endl ;
     for(int row = 0 ; row < 9 ; row++){
            for(int column = 0 ; column < 9 ; column++){
                    if(column > 0 && (column + 1) % 3 == 0 && (column + 1) != 9 )
                          cout <<grid[row][column] << " * " ;
             else    cout  <<grid[row][column]  <<"\t" ;                                                           
                    }
                    if( (row+1) % 3 == 0){cout <<endl ; 
                      cout << "---------------------------------------------------------------------" <<endl ;}
                    else  cout <<endl <<endl ;                    
            }

     }

int main(){
     print_grid() ;   
    return 0 ;         
    }

table

My question is: in the red area why does it print 2-3 spaces instead of "\t" ? why does '\t' change its length??

Caesar · Accepted Answer · 2014-01-25T15:06:53.057

1

The tab key doesn't have a certain length, all it does is advanced the cursor to the next stop in the document.

The length of the distance between stops can vary from system to system.

edited Jan 25 '14 at 15:06

answered Jan 25 '14 at 15:01

Caesar

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omg, i just changed "\t" to " " - 3 spaces, and it looks nice! – ERJAN Jan 25 '14 at 15:03
so i should learn the details of the language - because you can spend time looking for a bug - where this is just me not knowing the details. – ERJAN Jan 25 '14 at 16:25

toth · Answer 2 · 2014-01-25T15:08:53.817

Your code is fine. It's just the way tabs work in the console, they go to next tab stop which will be very 8 characters. If there are 5 characters already since last tab stop, it will only advance 3 characters.

You can check you get similar results by just using echo

echo -e "X\tX\nXXXXX\tX"
X       X
XXXXX   X

You can use two consecutive tabs if you want more space. If you want more control on alignment than that, you can stop using tabs and try using std::setw instead.

score 1 · Answer 3 · answered Jan 25 '14 at 15:03

1

You really don't want tab here you want to use iostream alignment manipulators.

answered Jan 25 '14 at 15:03

Paul Evans

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Formatting table - why does '\t' get changed?

3 Answers3